1. Field of the Invention
The present invention relates to an automatic exposure control device for use with a camera that incorporates a motor drive device to provide consistent continuous shooting operations.
2. Description of the Related Art
Cameras incorporating a motor drive device for providing continuous film advancement (i.e., continuous shooting) are known.
In a continuous shooting mode in the conventional motor driven camera, after the exposure of a first frame was completed and a main mirror was lowered, photometry and range finding were performed following the settling or stabilization of mirror vibration. Thereafter, a film was wound, a shutter charge sequence was completed and a next shutter release operation was commenced to expose another photograph.
However, with the conventional motor driven camera, because there was no signal indicating that the vibration of the mirror lowering operation had settled or stabilized, the time from a particular shutter release operation to the start time of range finding and photometry was an estimated time, and subsequent operational control was performed at that estimated time. For this reason, camera control was typically performed at the longest possible time at which range finding and photometry were possible in a particular photographic operation sequence.
With respect to the aforementioned time at which range finding and photometry were possible, for example, there is a known method in which the mirror raising time is detected, and camera control is performed according to a time resulting from a fixed time being added to the mirror raising time. The calculated amount of time serves as the amount of time at which range finding and photometry are possible after mirror lowering.
An example of another method for camera sequence control a proposal based on the principle that data from when a particular photometric operation was possible is used when photometry is not possible. Such a method is described in Japanese Laid-Open Patent Publication Number Hei 2-114245.
With the aforementioned conventional motor driven cameras and control methods, control was merely performed at the longest time at which range finding and photometry were possible. Moreover, when control was performed at a time value at which range finding and photometry were possible using the longest mirror lowering time even though the mirror raising time had been measured, the frame feed speed could not be accelerated.
Additionally, because motor drive time normally differs according to the degree of consumption of a power source (e.g., a battery), driving a motor in a single-lens reflex camera and control of the same is performed using the longest time at which range finding and photometry are possible. Accordingly, it is desirable that some type of countermeasure be devised to shorten the time during which range finding and photometry are carried out in order (1) to accelerate continuous shooting operations, and (2) to conserve precious battery life.